Electric gas-filled lamp with glow discharge



@cito E99 1926..

F. SCHRTER ELECTRIC GAS FILLED LAMP WITH GLOW DISCHARGE Filed Jan. 5, 1920 Mb MW MWLIQMMW Patented Oct. 19, 1926..

UNITED STATES tomo PATENT oFFlcE.

EEITz scHETEa, or BERLIN, GERMANY, AasIefNoE To SAFETY CAE HEATING a LIGHTING COMPANY, A CORPORATION or NEW JERSEY.

ELECTRIC GAS-FILLED LAMP WITH GLOW DISCHARGE.

Application led January 3, 1920, Serial No. 349,349, and in Germany May 4, 1915.

(GRANTED UNDER THE PROVISIONS F ACT 0F MARCH 3,1921, 41 STAT. L., 1313.)

This invention relates to gaseous conduct-ion lamps, and more particularly to lamps of the above nature having a content of a gas or gases of relatively high conductivityuction lamp characterized by a relativelyI high efficiency of conversion ofelectrical energy into light. Another object is to provide a gaseous conduction lamp in which an effective and etlicient use is made ot the various luminous regions in the glow discharge taking place within the lamp. Another object is to provide a lamp of the above character which will be automatically protective of itself against excessive current values passing therethrough. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and 'arrangement of parts as will be exemplified in the structure to be hereinafter described, and the scope of the application'of which will be indicated in the following claims.

In the accompanying drawing there is shown in the single figure a vertical central cross-sectional view of a possible embodiment of this invention.

As conducive to a clearer understanding ot this invention, it may at this point be noted that this invention relates particularly ot the above character adapted to vbe op.

erated upon ordinary commercial voltages, such for example as 220, 440 volts.

In the operation of a gaseous discharge device of the usual type there is found te exist a certain potential drop between the negative electrode or cathode and certain points in what is known as the negative glow of the discharge between thetwo electrodes.

' to lamps of the gaseous conduction type in- This potential difference is known asy the cathode fall of potential and will have what ma be termed a normal value when the cony ditions under which the device is operated are such that the entire cathodesurface is not utilized in the production of the luminous discharge between the electrodes and as long as the ions reaching and impingin upon the surface of the cathode are allowe to partake of their mean free and unobstructed path. This voltage drop or potential difference between the cathode and the negative glow will under the above conditions be substantially independent of the pressure of the gas within the device and is existent as long as the resultant glow is not distributed over the entire surface of the cathode but is conned to only a portion thereof. Such will be the case if the current values are Y relatively small.

It, however, the intensity of the current is increased to such an extent that the entire surface of the cathode becomes operative or effective to take part in the glow discharge and so that the entire cathode surface isv substantially entirely covered with the glow, the cathode fall of potential or, in other words. the potential difference between the cathode and negative glow is found to increase relatively rapidly with the increase in the intensity of the current. The same effect may be brought about if the surface of the cathode is so arranged with respect to the anode that the' ions impingng u on or reaching the cathode are prevente Jfrom taking their normal mean free path. Since the mean tref` path of the ions of the gas increases with a decrease in the gas pressure it is-found that the cathode fall of potentia increases with a decrease in the gas pressure, providing however that the entire suraceiof the cathode is covered with the glow discharge. The cathode fall of potential, thus increased above the normal value above set forth, may be termed an abnormal cathode :fall of potential.

In so far as I am aware, gaseous conduction lamps heretofore constructed and o erated are characterized by the fact that in their operation the cathode fall of potential is maintained at a normal value. The o eration of such prior gaseous conduction eviees'in this manner appears to have been devised for the purpose of maintaining at a minimum value the heating of the cathode and thereby also to minimize the disinte ration of the material of the cathode an to prevent the occlusion by the particles disintegrated from the cathode of the gases within the device.

As distinguished from such prior devices, it may besaid to be one of the features of this invention to maintain the cathode drop in potential at an abnormal value. Because of the phenomena that take place when the cathode drop in potential is maintained at an abnormal value, it has been found possible to give a gaseous conduction device an o erating characteristic in which the catho e drop in potential is found to increase as the current intensity increases. This action, it is believed, will be clearly understood from the considerations hereinbefore set forth. A gaseous conduction device or lamp having such a characteristic may, therefore, be connected directly into an electric circuit without necessitating the interposition of a protective resistance, since a tendency to `increase the current intensity passing through the device for any reason, such as, for example, an increase in the applied voltage, is met by a corresponding in crease in the cathode fall of potential. The cathode f'fall of potential may thus be considered as a counter electromotive force proportional directly to the current intensit 4 and acts to protect or safeguard automatica l the device against overloading. It will thus be seen that the inclusion of a resistance in the circuit of the lamp ma be entirely dispensed with and may be ma e only where it is desired to rovide additional safeguard- .ing of the devlce. Even where a resistance 0 may be inserted in the circuit of the lamp itwi be seen that the value of the resistance may be made4 exceedingly small because of the inherent self-protecting qualities of the gaseous conduction device itself and that hence only a minimum .and substantially in- .consequential dissipation of energy takes lace in the resistance where it happens to e included in the circuit.

- It will furthermore be seen that either by dispensing entirely with a protective resistance in the circuit of the lamp or by reducing its effective value for the reasons hereinabove set forth a greater portion of the applied or circuit voltage becomes available for utilization in the luminous column of the lamp, thus materially increasing the eiliciency of the device or lamp. In order further to eifectively utilize the increased energy consumed in that portion of the device where the cathode fall of potential is abnormal as hereinbefore set forth, provision is made in accordance with one of the features of this invention to make available as an effective and eiiicient source of light the glow covering the surface of the cathode,

shown at 1 a vessel adapted to contain a cony tent of a gas or gases of the helium group, as hereinbefore set forth, or may also contain a gas such as nitrogen, for example. The vessel 1 has mounted in its upper end an electrode 3 which may take the form of a sheet of metal such as iron or nickel, for example. The electrode 3, which takes the form of the anode in the operation of the device, may be mounted within the vessel 1 which mav be made of a suitable material, such as glass for example, in any suitable manner and a conductor 3a is adapted to make electrical connection from the exterior of the vessel l to the anode 3.

The vessel 1 at its lower end is preferably of greater cross section to provide a cathode receiving chamber, indicated at 2, which, as will be seen from the drawing, forms an extension of the main portion of the vessel 1. The cathode or other electrode adapted to cooperate with the anode 3 to bring about a luminous discharge within the gaseous contenty preferably takes the form of a substantially cylindrical sheet metal member 4 which may conveniently be mounted within the cathode receiving chamber 2 so as to be supported by the side walls of the latter, the cathode 4 forming in effect a lining for the cylindrical walls of the cathode chamber 2. The cathode 4 may be made of a suitable metal such as a metal of the alkali group, or may be made of an alloy including metals of the alkali group.

As will be more clearly hereinafter set forth, the glow discharge within the device when in operation covers substantially the entire surface of the cathode 4 and, as will be seen from the drawing, the surface of the cathode 4 that will thus be covered by the glow will be the interior cylindrical surface of the cathode 4. In order to utilize effectively the glow covering the surface of the *i cathode 4 there is mounted within the vessel 1 and preferably within the cathode chamber 2 a suitable reflector 5. The reflector 5 is conical in shape and may, for example, be made of glass or other suitable material adapted to resent on its exterior surface a surface we l adapted. for the reflection of light rays. The reflector 5 positioned substantially as illustratively v drawing will reflect the light rays indicated by the arrows a coming from `the luminous glow covering the surface of the cathode 4 outwardly as indicated by the arrows b, thus directing outwardly from the interior of the cathode chamber 2 the light rays set forth in the emanating from the glow which, as hereinv the ions, as well as `the rate of didusion thereof, is materially increased. With such an increase in the velocity and diffusion of the ions and with the lar e available cathode surface the lam w en in operation will be characterized by a glow which will substantially entirely cover the surface of the anode 4, under which conditions, as has been hereinbefore set forth at length, the cathode drop' of otential will assume a value characterize hereinbefore as abnormal. The lampis' thus not only made selfprotectiveelectrically since an increase Ain the current density will cause a corresponding increase in the cathode fall of potential acting in the nature of a counter E. M. F., but. also more efficient since the glow covering substantially entirely the entire surface of the cathode is made available as a source of light. `The redactor may be secured in place within the vessel' 1 or within the cathode chamber 2 by I any suitable means, such as a suspension 5, suitable openings 6 being provided to permit the xgaseous discharge to ass from one electrode to the other. A conductor, indicated diagrammatically at 4", serves to connect the cathode 4 with the exterior of the vessel 1. rllhe lamp, as hereinbefore described may also be operated upon alternating current as well as direct and itwill be seen that the luminous column or the luminous portions of the discharge which may extend upwardly through the vessel 1 to the anode 3 are supplemented as a Isource of light by the glow covering the cathode surface and resulting from the maintenance in the device ot an abnormal cathode fall of potential.

It will. thus be seen that there has been provided in this invention a gaseous conduction lamp in which the several objects hereinbefore set forth as well as others are attained and that many ladvantages are achieved. There has been provided a gaseous conduction lamp which yfunctions not only as an eflicient source of light, but also operates to substantially automatically protect itself against overloading electrically.

As manv possible embodiments might be made of the above invention and as many changes might be made in the embodiment above set forth, all matter hereinbetore settorth or shown in the accompanying drawing is to be init is to be understood that terpreted as illustrative and not in a limiting sense.

ll claim as my invention:

1. A gaseous conduction lamp, comprising, in combination, a vessel having translucent walls and containing a gas of relatively high conductivity, an anode mounted within said vessel, and .a cathode mounted within said vessel and adapted to cooperate with said anode to maintain therebetween a luminous discharge, said gas being at a pressure such that substantially the entire surlilv face of said cathode is covered with' theI glow forming part of said discharge in said gas. Y

2. A gaseous conduction lamp, comprising, in combination, a vessel having translucent walls and havinga gaseous content including a gas of the helium'group, an anode mounted within said vessel, and a cathode also mounted within said vessel having its effective surface so arranged with respect to said anode and said gas being at such a pressure that an increase in current due to a rise in voltage applied to said electrodes causes an increase inthe cathode fall of potential.

3. A gaseous conduction lamp, comprising, in combination, a vessel having translucent walls and containing a gas of high conductivity, an anode within said vessel, a cathode mounted within said vessel and having spaced oppositely disposed portions, the facing surfaces of which are adapted to cooperate with said anode to maintain therebetween a luminous discharge. said gas being at a pressure suchthat substantially the enlill) tire surface of said cathode is covered with theglow forming part of said discharge and means within said vessel and associate with said cathode for reflecting outwardly the light raysA emanating from the rglow covering the facing surfaces of said cathode.

4. A gaseous conduction lamp, comprising, in combination, a vessel having translucent walls and containing a gas of'relatively high conductivity,y an anode mounted within said vessel, a cathode having the form ot a hollow cylinder mounted within said vessel and adapted to cooperate with said anode to maintain therebetween a luminous discharge, said gas being at a pressure such that at least the ventire interior surface ot said cylindrical cathode'is covered with .the glow forming part of said discharge, and means mounted substantially within said .cylindrical cathode forvdirecting light rays emanating' from said glow on said interior surface of said cathode iny a direction substantially axial with respect Ito said cylindrical cathode.

5. The method of operating a gaseous conduction lamp having an anode and a cathode adapted to maintain a luminous dischar e in a gaseous content including a gas of hig Vthe anode to the cathode to a point where the cathode drop of potential becomes abnormal, whereby a further increase in the` current intensity is met with a substantially correspondingl increase in the cathode drop of potential.

6. The method of operating a gaseous conduction lamp having an anode and a cathode adapted to maintain a luminous discharge in a gaseous content including a gas of high conductivity, which consists in increasing the intensity of the current passing from the anode to the cathode to a point Where substantially the entire surface of the cathode is covered with the glow forming part of the luminous discharge between said anode and said cathode and in utilizing said glow covering the surface of said cathode to supplement as a source 0f light the luminous portions of said glow discharge.

ln testimony whereof I aix my signature.

JDR. FRITZ SCHRTER. 

